PD-L1 reverses depigmentation in Pmel-1 vitiligo mice by increasing the abundance of Tregs in the skin.

Programmed cell death 1 ligand 1 (PD-L1) is a ligand of programmed cell death 1 (PD-1) that functions as an immune checkpoint by down-regulating immune responses. To determine whether PD-L1 is a therapy target in vitiligo treatment, Pmel-1 vitiligo mice were treated with a PD-L1 fusion protein. Treatment with this fusion protein significantly reversed/suppressed depigmentation development in adult Pmel-1 mice. Mechanistically, enrichment of regulatory T cells (Treg) in the skin was detected after PD-L1 fusion protein treatment in Pmel-1 mice. Furthermore, Tregs abundance was also increased in both the spleen and circulation of Pmel-1 mice treated with PD-L1. These data indicate that PD-L1 protein therapy inhibits the immune response and reverses depigmentation development in Pmel-1 vitiligo mice.